Submitted to: International Symposium on Earthworm Ecology
Publication Type: Abstract Only
Publication Acceptance Date: September 1, 1998
Publication Date: N/A
The substitution of conservation tillage for conventional tillage practices can dramatically decrease surface runoff and losses of soil, nutrients, and pesticides in overland flow. Earthworm populations also frequently increase with a reduction in tillage intensity, which suggests that the effects of earthworm activity on soil structure and porosity may contribute eto the decrease in runoff. In particular, the size and number of L. terrestris (Lt) burrows found in some agricultural fields suggest that they may have a considerable effect on hydrology. In fact, a number of laboratory and field experiments have documented rapid transmission of water and surface-applied agricultural chemicals in Lt burrows. Most of these studies, however, have been conducted on unoccupied burrows and the sampling techniques disrupt the natural flow. This raises concern that the contribution of Lt burrows to water and chemical movement under field conditions may be overestimated. In this study, a Marriotte device was used to measure infiltration rate and 30 minute cumulative infiltration in individual, active, Lt burrows in fields in Coshocton, Ohio, USA and Bilsborrow, Lancashire, UK. Earthworms were expelled from half the burrows using formalin prior to conducting the infiltration experiments. Afterwards, plastic casts of the burrows were made so that relationships between burrow characteristics, earthworm size, and infiltration could be determined. Our results indicate that infiltration capacity of burrows with and without resident earthworms far exceeds what would be expected under natural rainfall conditions, suggesting that the high infiltration rates observed in the field and laboratory are realistic.